This invention relates to pressure dampers for use in fuel delivery systems for engines for motor vehicles.
In fuel rails for injector-based fuel injection systems, the various devices associated with the fuel system cause pressure waves in the fuel to propagate through the fuel rails. Such pressure waves, if occurring at the wrong time, may allow a small amount of fuel to leave the fuel rail and be injected into the engine at the time the injector is pulsed open. In addition, such pressure waves cause noise in the system that may be objectionable. Pressure pulses will give false readings to fuel pressure regulators by operating the regulator with a false indication of fuel pressure, which may result in fuel being bypassed and returned to the fuel tank.
A known pressure dampening system uses elastic walls forming the fuel supply line. As pressure pulses occur, the elastic walls function to dampen the pressure pulsations. Other pressure dampening systems use a pressure damper plugged in the end of a fuel rail with a pressure regulator at the other end. Still other pressure dampening systems use a compliant member operable to reduce peak pressure during injector firing events. The member is positioned in the fuel rail so as to not adversely affect the flow of fuel to an injector opening in the rail. The member is not free to rotate in the rail and the pressure pulses are dampened by the member, which is a pair of welded together shell halves with an enclosed airspace. Other pressure dampening systems use an in-line fuel pressure damper from the outlet of the fuel filter to the fuel rail. The damper is a pressure accumulator which operative to reduce transient pressure fluctuations induced by the fuel pump and the opening and closing of the fuel injectors.
Another dampening system utilizes an integral pressure damper that is attached to the fuel rail. The return tube is brazed to the rail and then at a convenient time in the assembly process the damper, which is a diaphragm, is attached to the return tube and crimped into position. The diaphragm operates to reduce audible operating noise produced by the injector pressure pulsations.
Still another dampening system uses a pulse damper in the fuel pump comprising a hollow body formed of a thin walled tube of flexible and resilient plastic material with heat sealed ends forming at least one chamber. The chamber carries a compressible gas to dampen pressure pulsations. Another dampening system uses a bellows modulator inside a gear rotor fuel pump for reducing pump noise by reducing the amplitude of fuel pressure pulses. Yet another system uses a bellows-like device at the junction of the lines of the flow path of the fluid from a fuel feed pump thereby forming a discontinuity in the flow path to reduce compressional vibrations of fuel being conveyed.
It would be beneficial to develop a dampening element that is relatively compact and inexpensive to manufacture and install.
Briefly, the present invention provides a fuel rail assembly. The assembly comprises a generally hollow fuel rail, a fluid dampening element and a clip. The fuel rail has an inner wall and a longitudinal rail axis extending therethrough. The fluid dampening element is disposed within the fuel rail and has a cross-sectional configuration. The clip includes an interior portion having a cross-sectional opening corresponding to and surrounding the cross-sectional configuration of the fluid dampening element and a plurality of exterior portions extending from the interior portion. Each of the plurality of exterior portions has an engagement end distal from the interior portion, with at least one of the engagement ends engaging the inner wall.
The present invention also provides a clip for retaining a dampening element in a conduit. The clip comprises a generally planar member having an interior portion having an opening adapted to receive and retain the dampening element and a plurality of exterior portions extending from the interior portion. Each of the plurality of exterior portions has an engagement end distal from the interior portion.
A method of reducing pressure pulsations in a fluid conduit is also provided. The method comprises providing a fluid conduit assembly having a generally hollow fluid conduit having an inner wall and a longitudinal conduit axis extending therethrough; a fluid dampening element having a wall and a longitudinal dampening element axis extending therethrough, the fluid dampening element being located within the fluid conduit, the dampening element axis being generally parallel with the conduit axis; and a clip engaging the inner wall and generally circumscribing at least a portion of the fluid dampening element, the clip retaining the fluid damper element away from the inner wall. The method further provides flowing pressurized fluid through the fluid conduit.
Further, a method of assembling a fuel rail assembly is also provided. The method comprises providing an elongated element having a first end and a second end; compressing a wall of the elongated element between the first and second ends toward a longitudinal axis of the elongated element in at least two locations along a length of the element, forming at least one generally rounded portion; inserting a clip onto each of the first and second ends, forming a member subassembly; and inserting the member subassembly into a fuel rail such that each of the clips engage the fuel rail and retain the elongated element away from a wall of the fuel rail.